Grading Solid Pseudopapillary Tumors of the Pancreas: the Fudan Prognostic Index

Background Ki-67 has been shown to predict outcome of patients with solid pseudopapillary tumor of the pancreas (SPTP) but has not been incorporated into a formal classification system to predict recurrence-free survival (RFS). Methods This is a retrospective cohort study of patients with histologically confirmed diagnosis of SPTP who had at least 1 year of follow-up at two tertiary academic centers. Survival data were assessed by Kaplan–Meier method and multivariable Cox regression model. Prognostic performance was compared among various systems. Results A total of 193 consecutive patients were included, ranging in age from 12 to 70 years (median 33 years). Seven patients (3.6%) developed tumor recurrence. The 3-, 5-, and 10-year RFS rates were estimated at 96.9%, 96.1%, and 94.8%, respectively. For the AJCC staging system, patients with stage I had similar prognosis to those with stage II. For the ENETS staging system, patients with stage I to III had similar prognosis. Grade based on Ki-67 was superior to both the AJCC and ENETS systems for predicting survival. Multivariate analysis revealed that large tumor size [> 10 cm; hazard ratio (HR), 6.177 95% confidence interval (CI), 1.289–29.603; P = 0.023] and Ki-67 (HR, 17.199 95% CI, 4.001–73.930; P < 0.001) were independent predictors for RFS. The Fudan Prognostic Index based on the combination of Ki-67 and tumor size showed excellent discrimination for RFS and was more accurate and informative than other grading/staging systems. Conclusion The Fudan Prognostic Index better predicts RFS compared with either Ki-67 alone or the current AJCC and ENETS TNM-based staging systems.